Just a note on this. Older hams will tell you that saying "73's" is the mark of a lid. It's also an indication of how the Tech class has made it's mark on traditional operations. In CW it's 73, always has been, where it was coined for use, and defined as "Best Wishes", not "Best Wish". It and many other numerical and Q codes are complete in useage, you don't need to add any modifers to them when speaking or writing, QSL?
73 de K0IOA/6 /M /MM
--ron